Lathyrus is a large genus of flowering plants in the legume family. These plants are known by the common names of vetchlings and sweet peas. Within the genus, there is considerable diversity. Gardeners cultivate several species, most notably L. odoratus or the garden sweet pea, and they can also be observed in abundance in the wild in many regions. People interested in growing members of this genus can obtain seeds from nurseries and through trades with other gardeners.
Some Lathyrus species are climbing plants, while others have a more shrubby growth habit. Both annuals and perennials are represented in the genus. The aromatic flowers can be white, maroon, red, peach, purple, and a variety of other colors, and the plants produce relatively unobtrusive leaves. The flowers develop into the distinctive seed pods associated with members of the legume family. If left in place on the plant, they will pop open to disperse the seeds once the seeds are fully matured.
Over 150 species are classified in this genus. They are found throughout the western hemisphere, favoring temperate climates although they can be found in other zones as well. Depending on the species, levels of drought tolerance vary, as does the ability to tolerate harsh soil conditions. Some species are fragile and need full sun and shelter to grow, while others are more rugged and do not object to wind and shade.
In addition to being grown decoratively in the garden, several species are also food sources. The seeds of some Lathyrus species are edible and may be used to produce high protein flour, most notably in some traditional European cuisines. Other species have starchy edible roots with food uses. The aromatic flowers are popular as cut flowers in some areas.
Many of the cultivars developed for gardening are susceptible to insect and fungus infestation. Lathyrus species need to be grown in clean soil where peas have not been growing for at least one year, and they should be provided with plenty of light to deter fungi from developing. Spacing plants well is recommended to prevent the creation of shady pockets that may attract pests, and if plants become diseased, they should be removed and securely disposed of to prevent the spread of infection.
Lathyrus seeds are readily available. They can be started indoors in humid conditions in the spring and planted out after the last chance of frost has passed. Providing some fertilizer to promote growth can be helpful, and in the case of perennials, trimming to keep the plant compact and bushy, rather than leggy, is recommended.